I see the same problems with Git and Floobits frequently. Here are some of my basic fixes for common errors. Most errors seem to occur with the partner who did not initiate the Floobits session.
fatal: Not a git repository (or any parent up to mount point /home/kate)
Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)
$ git init
Floobits has put another clone on your computer, which you have made changes to, and now need to redirect the git commits/pushes from the new files.
$ git remote add <branch name> https://github.com/barbbella/yourRepo
If you see the following:
! [rejected] master -> master (fetch first)
$ git pull https:// github.com/barbbella/yourRepo
Manually correct conflicts & repeat. Git commit will merge your changes.